:root {
    --primary-color: #0d6efd;
    --secondary-color: #6c757d;
    --success-color: #198754;
    --danger-color: #dc3545;
    --light-color: #f8f9fa;
    --dark-color: #212529;
}

body {
    background: linear-gradient(135deg, #667eea, #764ba2);
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    min-height: 100vh;
    display: flex;
    align-items: center;
}

.login-card {
    width: 100%;
    max-width: 400px;
    border-radius: 15px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
    background-color: rgba(255, 255, 255, 0.95);
}

.login-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

.login-header {
    color: var(--dark-color);
    font-weight: 600;
    letter-spacing: 1px;
}

.form-control {
    border: none;
    border-bottom: 2px solid #dee2e6;
    border-radius: 0;
    padding-left: 35px; /* 增加左侧内边距给图标留空间 */
    padding-right: 0;
    background-color: transparent;
}

.form-control:focus {
    box-shadow: none;
    border-bottom-color: var(--primary-color);
}

.btn-login {
    background: linear-gradient(to right, var(--primary-color), #0b5ed7);
    border: none;
    letter-spacing: 1px;
    font-weight: 600;
    transition: all 0.3s;
}

.btn-login:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(13, 110, 253, 0.3);
}

.error-message {
    height: 24px;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.error-message.show {
    opacity: 1;
}

.input-icon {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    left: 0;
    color: #6c757d;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 5;
}

.input-group {
    position: relative;
}

.show-password {
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    cursor: pointer;
    color: #6c757d;
    transition: color 0.2s;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 5;
}

.show-password:hover {
    color: var(--primary-color);
}
